JP4943378B2 - Condensate demineralization method and condensate demineralization apparatus - Google Patents

Description

  The present invention relates to condensate treatment by a condensate demineralizer of a nuclear power plant, and stably obtains high-purity treated water quality having a low concentration of sulfate ions derived from organic impurities eluted from a cation exchange resin over a long period of time. The present invention relates to a condensate desalination method and apparatus.

  In a nuclear power plant, after generating electricity with steam generated in a nuclear reactor or a steam generator, the steam is cooled with seawater, and the condensate is treated with a condensate demineralizer using an ion exchange resin. Or water is supplied to the steam generator. This condensate contains seawater components that flow into the condensate system, suspended corrosion products (hereinafter referred to as clads) mainly composed of iron oxides generated from plant components, and ionic impurities. there is a possibility. In order to remove impurities in the condensate and obtain a high-purity treated water quality, the nuclear power plant is provided with a condensate demineralizer that demineralizes the condensate with an ion exchange resin. Examples of the ion exchange resin used in the condensate demineralizer include a cation exchange resin that adsorbs cations and an anion exchange resin that adsorbs anions, which are used in combination.

  In this condensate desalination apparatus, when a cation exchange resin and an anion exchange resin are used in combination, usually a gel cation exchange resin and a gel anion exchange resin are combined, or a porous cation exchange resin and a porous anion. Used in combination with exchange resin. In general, gel type resins have low osmotic pressure resistance, and porous type resins have low wear resistance. Considering these drawbacks, gel type resins are used in condensate demineralizers for plants that frequently perform backwash regeneration. However, a porous resin is used in a plant that frequently performs drug regeneration. In particular, the porous resin has low wear resistance, and the resin is transferred when transferring between the demineralization tower containing the ion exchange resin bed and the regeneration tower for regenerating the ion exchange resin in the condensate demineralizer. In order to eliminate the clad adhering to the surface of the cation exchange resin as in the BWR nuclear power plant because the surface of the resin particle is damaged or the resin particle is crushed due to the contact between the particles or the resin particle and the metal material. In a plant that performs backwashing, a gel-type cation exchange resin and a gel-type anion exchange resin having good wear resistance are used in combination.

  In addition, the porous resin has a denser resin matrix structure than the gel resin, so that the diffusion rate of adsorbed ions into the particles is smaller than that of the gel resin, and the performance is poor in terms of reaction rate and regeneration efficiency. . For this reason, when the porous resin is used in a condensate demineralizer, it is necessary to design the apparatus in consideration of the characteristics of the porous resin, such as increasing the regeneration level (chemical use amount).

The ion exchange resin used in the condensate demineralizer of a nuclear power plant has a high ability to remove ion components such as seawater components represented by NaCl flowing from the upstream side, but polystyrene sulfonic acid is removed from the cation exchange resin. There is a problem that organic impurities (hereinafter referred to as TOC) as a main component are eluted. When this TOC is brought into a nuclear reactor or a steam generator, sulfate ions are generated, which causes the water quality of the nuclear reactor or the steam generator to deteriorate.
Therefore, in order to obtain a high-purity reactor or steam generator water quality, it is necessary to reduce the amount of TOC leaked from the desalting tower filled with the ion exchange resin.

As a method for solving these problems, as disclosed in Patent Document 1 (Japanese Patent Application Laid-Open No. 11-352283), the degree of cross-linking is usually 12 to 12%, which is higher than the range of 8% to 10%. A method of applying a 16% strongly acidic gel-type cation exchange resin, as disclosed in Patent Document 2 (Japanese Patent Laid-Open No. 2001-314855), an anion exchange resin is arranged on the lower layer of the ion exchange resin bed to form a cation A method for adsorbing TOC eluted from an exchange resin, as disclosed in Patent Document 3 (Japanese Patent Laid-Open No. 8-224579), a porous anion exchange having a strongly acidic gel type cation exchange resin and a Gaussian particle size distribution A method of forming a mixed bed with resin has been proposed.
Japanese Patent Laid-Open No. 11-352283 JP 2001-314855 A JP-A-8-224579

However, even if a strongly acidic gel type cation exchange resin having a high degree of crosslinking is used, oxidative degradation progresses over a long period of use and TOC elution gradually increases. Inevitable.
Further, in the method of disposing the anion exchange resin in the lower layer portion of the ion exchange resin bed, the low molecular weight TOC eluted from the cation exchange resin can be reduced, but the removal ability of the high molecular weight TOC is not sufficient.
Also, porous anion exchange resins have macropores, so they have some TOC adsorption capacity, but they are commonly used in condensate demineralizers in nuclear power plants. In the porous anion exchange resin such as PA312, the porous ion exchange resin has macropores, and therefore the resin matrix portion has a very dense structure, and the occlusion ability into the resin grains is never high.

  The present invention has been made in view of the above circumstances, and in condensate treatment by a condensate demineralizer of a nuclear power plant, it is possible to obtain a high-purity treated water quality having a low TOC-derived sulfate ion concentration eluted from a cation exchange resin. An object of the present invention is to provide a condensate demineralization method and apparatus.

In order to achieve the above object, the present invention provides a condensate desalination method for desalinating condensate of a nuclear power plant with an ion exchange resin.
It consists of a mixed bed in which a strongly acidic gel type cation exchange resin and a strongly basic type 1 porous anion exchange resin having a crosslinking degree in the range of 1% to 4% are uniformly mixed, and the mixed bed comprises the anion resin. The organic matter eluted from the cation exchange resin by bringing condensate into contact with an ion exchange resin bed having a mixed bed uniformly mixed so that the abundance ratio is within the design standard value ± 5% over the entire mixed bed. Provided is a condensate desalting method characterized by performing desalting while removing .

Further, the present invention is a condensate desalination method for desalinating condensate of a nuclear power plant with an ion exchange resin.
(A) a mixed bed in which a strongly acidic gel type cation exchange resin and a strongly basic type 1 porous anion exchange resin having a crosslinking degree in the range of 1% to 4% are uniformly mixed, An upper layer portion composed of a mixed bed uniformly mixed so that the abundance ratio of the anionic resin is within a design standard value ± 5% over the entire mixed bed;
(B) a condensate dewatering process wherein decondensation is performed while removing the organic substances eluted from the cation exchange resin by bringing the condensate into contact with an ion exchange resin bed having a lower layer made of an anion exchange resin. A salt method is provided.

Further, the present invention is a condensate desalination method for desalinating condensate of a nuclear power plant with an ion exchange resin.
(A) an upper layer made of a cation exchange resin;
(B) a mixed bed in which a strongly acidic gel type cation exchange resin and a strongly basic type 1 porous anion exchange resin having a crosslinking degree in the range of 1% to 4% are uniformly mixed, A condensate is brought into contact with an ion exchange resin bed having a lower layer portion composed of a mixed bed uniformly mixed so that the abundance ratio of the anion resin is within a design standard value ± 5% over the entire mixed bed. A condensate demineralization method is provided, wherein a demineralization treatment is performed while removing organic substances eluted from the cation exchange resin .

Further, the present invention is a condensate desalination method for desalinating condensate of a nuclear power plant with an ion exchange resin.
(A) an upper layer made of a cation exchange resin;
(B) a mixed bed in which a strongly acidic gel type cation exchange resin and a strongly basic type 1 porous anion exchange resin having a crosslinking degree in the range of 1% to 4% are uniformly mixed, A middle layer portion composed of a mixed bed uniformly mixed so that the abundance ratio of the anionic resin is within a design standard value ± 5% over the entire mixed bed;
(C) A demineralization treatment of the condensate is performed while removing the organic substances eluted from the cation exchange resin by bringing the condensate into contact with an ion exchange resin bed having a lower layer portion made of an anion exchange resin. A condensate desalination method is provided.

In the condensate desalting method of the present invention, the organic substance preferably contains polystyrene sulfonic acid.
In the condensate desalting method of the present invention, it is preferable to use a strongly acidic gel type cation exchange resin having a crosslinking degree in the range of 12% to 16% as the cation exchange resin.

  In the condensate desalting method of the present invention, it is preferable to use a strongly acidic gel type cation exchange resin having a degree of crosslinking in the range of 4 to 7% as the cation exchange resin.

The present invention also relates to a condensate demineralizer for a nuclear power plant that demineralizes condensate with an ion exchange resin.
Condensate is brought into contact with an ion exchange resin bed having a mixed bed in which a strongly acidic gel type cation exchange resin and a strongly basic type 1 porous anion exchange resin having a crosslinking degree in the range of 1% to 4% are uniformly mixed. A condensate demineralization apparatus is provided that performs a desalting treatment while removing organic substances eluted from the cation exchange resin .

The present invention also provides a condensate demineralizer for a nuclear power plant that demineralizes condensate with an ion exchange resin.
(A) an upper layer portion comprising a mixed bed in which a strongly acidic gel type cation exchange resin and a strongly basic type 1 porous anion exchange resin having a crosslinking degree in the range of 1% to 4% are uniformly mixed;
(B) a condensate dewatering process wherein decondensation is performed while removing the organic substances eluted from the cation exchange resin by bringing the condensate into contact with an ion exchange resin bed having a lower layer made of an anion exchange resin. A salt device is provided.

The present invention also relates to a condensate demineralizer for a nuclear power plant that demineralizes condensate with an ion exchange resin.
(A) an upper layer made of a cation exchange resin;
(B) having a lower layer portion comprising a mixed bed in which a strongly acidic gel type cation exchange resin and a strongly basic type 1 porous anion exchange resin having a crosslinking degree in the range of 1% to 4% are uniformly mixed. Provided is a condensate demineralization apparatus which performs a desalting treatment while bringing condensed water into contact with an ion exchange resin bed and removing organic substances eluted from the cation exchange resin .

The present invention also relates to a condensate demineralizer for a nuclear power plant that demineralizes condensate with an ion exchange resin.
(A) an upper layer made of a cation exchange resin;
(B) a middle layer portion comprising a mixed bed in which a strongly acidic gel type cation exchange resin and a strongly basic type 1 porous anion exchange resin having a crosslinking degree in the range of 1% to 4% are uniformly mixed;
(C) Condensate dewatering, wherein decondensation treatment is performed while removing the organic substances eluted from the cation exchange resin by bringing the condensate into contact with an ion exchange resin bed having a lower layer portion made of an anion exchange resin. A salt device is provided.

In the condensate demineralization apparatus of the present invention, it is preferable that the organic substance contains polystyrene sulfonic acid.
In the condensate demineralization apparatus of the present invention, it is preferable to use a strongly acidic gel type cation exchange resin having a crosslinking degree in the range of 12% to 16% as the cation exchange resin.

  In the condensate demineralization apparatus of the present invention, it is preferable to use a strongly acidic gel type cation exchange resin having a degree of crosslinking in the range of 4 to 7% as the cation exchange resin.

  According to the present invention, an ion exchange resin having a mixed bed in which a strongly acidic gel type cation exchange resin and a strongly basic type 1 porous anion exchange resin having a crosslinking degree in the range of 1% to 4% are uniformly mixed. Condensate is desalted by bringing the condensate into contact with the floor, so that the clad in the condensate can be removed by the cation exchange resin, and the TOC eluted from the cation exchange resin can be removed by the anion exchange resin. Can be removed. In particular, by using a strongly basic type 1 porous anion exchange resin having a crosslinking degree in the range of 1% to 4%, it is possible to increase the TOC removal capability, and to reduce the TOC-derived sulfate ion concentration and high purity. Can be obtained.

Hereinafter, although an embodiment of the present invention is described with reference to drawings, the present invention is not limited to this.
FIG. 1 is a schematic flow configuration diagram illustrating an example of a BWR nuclear power plant. In FIG. 1, 1 is a nuclear reactor, 2 and 3 are turbines, 4 is a moisture separator, 5 is a condenser, 6 is a condensate filtration device, 7 is a condensate demineralizer, and 8 is a reactor purification system. Represents.

  In this BWR nuclear power plant, steam is generated in the nuclear reactor 1, and the turbines 2 and 3 are rotated by the steam to generate power. The steam emitted from the turbine 3 is cooled by the condenser 5 and returned to water, purified by the condensate filter 6 and the condensate demineralizer 7 as purification equipment, and supplied to the nuclear reactor 1. As with the BWR nuclear power plant, the steam generator side of the pressurized water (PWR) nuclear power plant generates steam with the steam generator, generates power with the turbine, returns the steam to water with the condenser, and purifies it. The water is then supplied to the steam generator.

FIG. 2 is a schematic flow configuration diagram showing an embodiment of the condensate demineralization apparatus of the present invention. In FIG. 2, 7 is a condensate demineralizer, 10 is a desalting tower, 11 is an ion exchange resin bed, 12 is a resin strainer, and 13 is a recirculation pump. This condensate demineralizer 7 treats condensate at a flow rate of 2000 to 7000 m ³ / h in 3 to 10 demineralizers 10. One desalting tower 10 is filled with 2000 to 15000 L of ion exchange resin at a treatment flow rate to form an ion exchange resin bed 11. The floor height of the ion exchange resin bed 11 is in the range of 90 to 200 cm, and is usually about 100 cm. The water line flow velocity is in the range of 50 to 200 m / h, and is usually about 100 m / h.

3A to 3D are schematic configuration diagrams illustrating the structure of the ion exchange resin bed 11 in the condensate demineralizer of the present invention.
In the first example shown in FIG. 3 (A), a strongly acidic gel type cation exchange resin and a strongly basic type 1 porous type anion exchange resin having a crosslinking degree in the range of 1% to 4% were uniformly mixed. An ion exchange resin bed 11 is formed by the mixed bed 14.

In the second example shown in FIG.
(A) an upper layer portion 15a composed of a mixed bed in which a strongly acidic gel type cation exchange resin and a strongly basic type 1 porous anion exchange resin having a crosslinking degree in the range of 1% to 4% are uniformly mixed;
(B) The ion exchange resin bed 11 is formed from the lower layer part 15b which consists of an anion exchange resin.

In the third example shown in FIG.
(A) an upper layer portion 16a made of a cation exchange resin;
(B) From a strongly acidic gel type cation exchange resin and a lower layer portion 16b comprising a mixed bed in which a strongly basic type 1 porous anion exchange resin having a crosslinking degree in the range of 1% to 4% is uniformly mixed. An ion exchange resin bed 11 is formed.

In the fourth example shown in FIG.
(A) an upper layer portion 17a made of a cation exchange resin;
(B) a middle layer portion 17b comprising a mixed bed in which a strongly acidic gel type cation exchange resin and a strongly basic type 1 porous anion exchange resin having a crosslinking degree in the range of 1% to 4% are uniformly mixed;
(C) The lower layer part 17c which consists of anion exchange resin is arrange | positioned in order, and the ion exchange resin bed 11 of a 3 layer structure is formed.

In the present invention, the “degree of crosslinking” refers to the mass ratio of DVB as the crosslinking agent in the total raw material when a resin copolymer is produced from styrene and divinylbenzene (DVB) as the crosslinking agent. Point to.
Most of the characteristics of the ion exchange resin are determined by the degree of crosslinking, which is the addition ratio of divinylbenzene. In particular, the moisture content and ion exchange capacity have a clear correlation with the degree of crosslinking. The relationship between the degree of crosslinking and various properties is generally as follows. A resin with a low degree of cross-linking has a smaller exchange capacity per unit volume in a wet state and a higher water content than a resin with a high degree of cross-linking. Large micropore diameter, excellent reaction rate, and excellent regeneration characteristics. On the other hand, physical strength is low and oxidation resistance is poor. After grasping these characteristics, an ion exchange resin having an optimum degree of crosslinking is selected according to the required performance and used for various water treatment facilities.

  Porous anion exchange resins such as IRA900 of Rohm and Haas Japan Co., Ltd. and PA312 of Mitsubishi Chemical Corporation, which are normally used in condensate demineralizers of nuclear power plants, have a degree of cross-linking of 6 to 8% and are porous. Since the type ion exchange resin has macropores, the resin matrix part has a very dense structure, and if the resin matrix is dense, it is difficult to diffuse into the grains, so the organic matter removal ability is not sufficient. .

  In the present invention, a strongly basic type 1 porous anion exchange resin having a crosslinking degree of 1% to 4% is combined with a cation exchange resin and used as the ion exchange resin bed 11. Since this low-crosslinking porous anion exchange resin has a rough resin matrix, it has an ability to remove organic substances, particularly cation exchange resin eluate (TOC) mainly composed of polystyrenesulfonic acid having a molecular weight of 1000 or more. Since it becomes high, the water quality of high purity will be obtained.

  Here, characteristics of the porous anion exchange resin and the gel anion exchange resin will be described. The granular ion exchange resins are roughly classified into two types of ion exchange resins derived from the production method. A copolymer is prepared by suspension polymerization of styrene and divinylbenzene, and a transparent gel-type ion exchange resin into which functional groups have been introduced, and an organic solvent that is insoluble in water and dissolves styrene well during suspension polymerization are added. And a porous ion exchange resin having macropores produced by removal after polymerization. The discrimination method is very easy, and the transparent sphere can be discriminated as a gel type resin and the opaque sphere can be discriminated as a porous type resin. In addition to visual observation, when using a stereomicroscope and observing with transmitted light, light is transmitted and the entire resin particle can be observed. Gel resin, when reflected light is diffusely reflected and appears black. It is a porous resin.

The average pore diameter of the gel-type ion exchange resin is several liters and the specific surface area is less than 1 m ² / g, whereas the average pore diameter of the porous resin is several tens to several hundreds liters and the specific surface area is also several tens to several hundreds m. It is very different from about ² / g.

  There is no problem with the structure of gel type resin to adsorb normal ions such as sodium ion and chlorine ion, but gel type resin and porous type resin can be used for high molecular weight substances compared to ions such as organic matter. There are differences in removal characteristics due to the structure.

Since the anion exchange resin has a quaternary ammonium group, the resin matrix is positively charged. Therefore, adsorption to negatively charged organic substances is expected. In particular, polystyrene sulfonic acid having a molecular weight of several hundred to several tens of thousands elutes from the cation exchange resin due to oxidative degradation of the base structure. Since it has a negative charge, adsorption with an anion exchange resin is expected, but in the case of gel type resin, the average pore diameter is as small as several kilometers, so it has only adsorption capacity on the surface of the resin particles, and the surface area is also large. Since it is as small as less than 1 m ² / g, the removal capability is low.

On the other hand, the porous resin has an average pore diameter of several tens to several hundreds of liters and a specific surface area of several tens to several hundreds m ² / g, which is two or more orders of magnitude larger than the gel type resin. It can be said that the incorporation into the inside of the grain is easy.

  In particular, porous type anion exchange resins with a low degree of crosslinking are inferior in wear resistance, so they could be solved by devising operational methods to combine with gel type cation exchange resins that need to be backwashed frequently. . The wear of the ion exchange resin mainly occurs when the resin particles are transferred or when scrubbing with air is performed. Therefore, when the resin particles are transferred, water is preliminarily applied to the tank on the resin particle receiving side in the resin particle transfer so that the resin particles do not directly collide with the metal material, or the slurry concentration during the resin transfer is lowered. Only the cation exchange resin with a large amount of clad on the surface after the cation exchange resin and the anion exchange resin are separated by air scrubbing performed in a resin mixed state. By taking measures such as implementing it, it is possible to avoid the disadvantages of the physical characteristics of the porous anion exchange resin having a crosslinking degree of 1% to 4%.

  On the other hand, the low-crosslinking degree resin has the drawback that the exchange capacity is small in addition to the above-mentioned strength. The exchange capacity of a porous anion exchange resin with a degree of cross-linking of 8% that is typically used is about 1.0 eq / L, whereas the exchange capacity of a 1.5% porous anion exchange resin is about 0 About 5 eq / L. However, in nuclear power plants, the concentration of impurities in the condensate can be reduced by making the condenser made of titanium, maintaining and managing the purity of the pure water to be replenished, and increasing the purity of chemicals such as ammonia to be injected. It is kept very low, and the ion load amount due to water flow for one year is about 0.05 eq / L at most. Therefore, if it is about 0.5 eq / L, even if it assumes that an effective utilization rate is low and 50%, it can be used for 5 years or more, and it can be evaluated that there is no problem.

  For the above reasons, the use of a porous type 1 anion exchange resin having a cross-linking degree of 1% to 4% makes it possible to exhibit a high TOC adsorption capacity.

  Examples of strongly basic type 1 porous anion exchange resins used in the present invention include PA306 (corresponding to a crosslinking degree of 3%) and PA308 (corresponding to a crosslinking degree of 4%) and Dow Chemical Japan Co., Ltd. sold by Mitsubishi Chemical Corporation. TAN1 (corresponding to a crosslinking degree of 1.5%), etc., may be applied.

Furthermore, the quality of treated water with higher purity can be obtained by devising the method of forming the ion exchange resin bed 11 in the desalting tower.
The condensate demineralizer is usually used in a mixed bed state in which a cation exchange resin and an anion exchange resin are mixed (see FIG. 3A). This is intended to efficiently cause a reaction in which H ions and OH ions released become water when the H type cation exchange resin and the OH type anion exchange resin undergo an ion exchange reaction. However, at present, the concentration of impurities flowing in is kept extremely low, and at present, sulfate ions derived from TOC such as polystyrene sulfonic acid eluted from cation exchange resins occupy most of impurities in nuclear reactors and steam generators. Therefore, it is more demanded to lower the TOC concentration from the cation exchange resin. Therefore, it is desirable to devise the arrangement of the ion exchange resin in the desalting tower. There are the following three methods.

(1) A condensate treatment is performed by arranging a mixed bed of cation exchange resin and anion exchange resin in the upper layer of the desalting tower and forming an ion exchange resin bed in the lower layer to form an ion exchange resin bed. Water desalination method (see FIG. 3B).
(2) The resin distribution in the desalting tower is formed by arranging a cation exchange resin in the upper layer part and a mixed bed of cation exchange resin and anion exchange resin in the lower layer part to form an ion exchange resin bed and condensing water. A condensate desalting method for treating (see FIG. 3C).
(3) The resin distribution in the desalting tower is a three-layer structure in which a cation exchange resin is arranged in the upper layer, a mixed bed of cation exchange resin and anion exchange resin is arranged in the intermediate layer, and an anion exchange resin is arranged in the lower layer. A condensate demineralization method for forming condensate by forming an ion exchange resin bed (see FIG. 3D).

By performing the ion exchange resin bed forming method as described above in combination with a porous type 1 anion exchange resin having a crosslinking degree of 1 to 4%, a higher-purity water quality can be obtained. These ion exchange resin bed arrangement methods can be easily formed by using a regeneration facility such as a cation exchange resin regeneration tower, an anion exchange resin regeneration tower, or a resin reservoir attached to a condensate demineralizer. it can.
In addition to the cation exchange resin to be used, the following two are considered in addition to the strongly acidic gel cation exchange resin having a crosslinking degree of 8 to 10% which is used as a standard.

(1) A condensate desalination method in which a condensate is treated by forming an ion exchange resin bed using a strongly acidic gel-type cation exchange resin having a crosslinking degree of 12 to 16% as a cation exchange resin to be combined.
(2) A condensate desalination method in which a condensate is treated by forming an ion exchange resin bed using a strongly acidic gel type cation exchange resin having a cross-linking degree of 4 to 7% as a cation exchange resin to be combined.

  According to the present invention, an ion exchange resin having a mixed bed in which a strongly acidic gel type cation exchange resin and a strongly basic type 1 porous anion exchange resin having a crosslinking degree in the range of 1% to 4% are uniformly mixed. Condensate is desalted by bringing the condensate into contact with the floor, so that the clad in the condensate can be removed by the cation exchange resin, and the TOC eluted from the cation exchange resin can be removed by the anion exchange resin. Can be removed. In particular, by using a strongly basic type 1 porous anion exchange resin having a crosslinking degree in the range of 1% to 4%, it is possible to increase the TOC removal capability, and to reduce the TOC-derived sulfate ion concentration and high purity. Can be obtained.

  In the BWR nuclear power plant, it is required to maintain the reactor water quality with high purity in order to suppress corrosion of the reactor constituent materials and maintain soundness. The main impurity in the reactor water is sulfate ions, and this source is TOC from the cation exchange resin used in the condensate demineralizer. In particular, when the condensate demineralizer outlet water is supplied to the reactor, the impurity concentration is concentrated 50 to 100 times by evaporation in the reactor, so the TOC in the condensate outlet water is reduced even slightly. There are great benefits to doing.

  When the ion exchange resin used in the condensate demineralizer is new, the sulfuric acid ion concentration in the reactor water is approximately 1 μg / L, and the oxidative deterioration of the cation exchange resin progresses over time and the cation exchange resin. The organic impurities that are eluted from the water increase and increase to about 5 μg / L at the end of the ion exchange resin life, so the ion exchange resin is replaced.

Therefore, if the amount of TOC leakage from the condensate demineralizer can be reduced, the concentration of sulfate ions in the reactor water can be reduced, the diameter of the reactor constituent material can be maintained, and the life of the ion exchange resin can be increased. In addition to being economical and advantageous, the amount of radioactive waste generated can be reduced, which is very advantageous.
Furthermore, in order to maintain the integrity of the reactor constituent materials, it has recently been demanded that the reactor water quality be further purified. Various countermeasures have been studied for this purpose, but the present invention is a very effective method from this viewpoint.

  Hereinafter, the present invention will be described specifically by way of examples. However, the present invention is not limited to this example.

[Example 1]
Oxidizing the strongly acidic gel-type cation exchange resin HCR-W2-H with a crosslinking degree of 8%, which is an ion exchange resin (manufactured by Dow Chemical Japan Co., Ltd.) widely used in condensate demineralizers of nuclear power plants. In combination with various anion exchange resins, the eluted TOC concentration was measured. In the oxidation treatment method, first, a cationic resin is immersed in an aqueous ferric sulfate solution, iron ions are loaded at about 15 g / L, and this is immersed in an aqueous 0.5% hydrogen peroxide solution at 40 ° C. for 6 hours. Thereafter, it was thoroughly washed with water.

<Case 1>
A mixed bed of the cation exchange resin + anion exchange resin SBR-PC-OH manufactured by Dow Chemical.

<Case 2>
Mixed bed of the cation exchange resin + 6% porous type anion exchange resin PA312 manufactured by Mitsubishi Chemical.

<Case 3>
Mixed bed of the cation exchange resin + 4% cross-linked porous anion exchange resin PA308 manufactured by Mitsubishi Chemical.

<Case 4>
A mixed bed of the cation exchange resin + TAN1 made by Dow Chemical, a porous anion exchange resin having a crosslinking degree of 1.5%.

  The test apparatus used is as shown in FIG. A column having an inner diameter of 25 mm is filled with cation exchange resin and anion exchange resin mixed at a volume ratio of 2/1, pure water is adjusted to 40 ° C., and circulation operation is performed. Column outlet water was collected periodically, and the TOC concentration was measured with TOC-5000, which is a TOC meter manufactured by Shimadzu Corporation, to calculate the TOC elution rate. The results are shown in Table 1.

  As can be seen from Table 1, Case 3 and Case 4, which are combinations of ion exchange resins according to the present invention, have a lower sulfuric acid concentration in water than Case 1 and Case 2 of the prior art, and excellent TOC removal performance. It was confirmed that

[Example 2]
Oxidation treatment of strongly acidic gel-type cation exchange resin HCR-W2-H with a crosslinking degree of 8%, which is an ion exchange resin (manufactured by Dow Chemical Japan Co., Ltd.) widely used in condensate demineralizers of nuclear power plants In combination with the TAN1 anion exchange resin made by Dow Chemical, which has a degree of cross-linking of 1.5% according to the present invention, and SBR-PC-OH made by Dow Chemical, which is conventionally used, Each ion exchange resin bed of case 8 was formed, and the eluted TOC concentration was measured. In the oxidation treatment method, first, a cationic resin is immersed in an aqueous ferric sulfate solution, iron ions are loaded at about 15 g / L, and this is immersed in an aqueous 0.5% hydrogen peroxide solution at 40 ° C. for 6 hours. Thereafter, it was thoroughly washed with water.

<Case 5>
An ion exchange resin bed comprising a mixed bed of cation exchange resin HCR-W2 and anion exchange resin SPR-PC-OH.

<Case 6>
An ion exchange resin bed comprising a mixed bed of cation exchange resin HCR-W2 and anion exchange resin TAN1.

<Case 7>
An ion exchange resin resin bed in which the cation exchange resin HCR-W2 is arranged in the upper layer portion and a mixed bed of the cation exchange resin HCR-W2 and the anion exchange resin TAN1 is arranged in the lower layer portion.

<Case 8>
An ion exchange resin bed in which a mixed bed of cation exchange resin HCR-W2 and anion exchange resin TAN1 is arranged in the upper layer part, and an anion exchange resin TAN1 is arranged in the lower layer part.

The test was carried out by simulating the same conditions as the actual plant, assuming that the quality of the treated water, temperature, ion exchange resin bed height, and water flow velocity were the same as the actual plant.
A mixed bed in which a cation exchange resin and an anion exchange resin are mixed at a volume ratio of 2/1 in a column having an inner diameter of 25 mm, and half of the cation exchange resin is disposed in the upper layer portion, and the remaining cation exchange resin and anion exchange resin are mixed. The ion exchange resin bed of Example 4 in which the floor was arranged in the lower layer part, and Example 5 in which half of the anion exchange resin was arranged in the lower layer part and the remaining anion exchange resin and the entire amount of the cation exchange resin were arranged in the upper layer part as a mixed bed The pure water of 45 ° C. with a conductivity of 0.006 mS / m is passed through the ion-exchange resin bed, and the ion concentration in the treated water is the sulfate ion produced by irradiating the treated water with ultraviolet rays to decompose the contained TOC. The concentration was analyzed by ion chromatography. The results are shown in Table 2.

  As can be seen from Table 2, it was confirmed that Cases 6 to 8 according to the present invention have a lower sulfuric acid concentration and superior TOC removal performance as compared to Case 5 which is the prior art.

It is a schematic flow block diagram which shows an example of a BWR nuclear power plant. It is a schematic flow block diagram which shows one Embodiment of the condensate demineralization apparatus of this invention. It is a schematic block diagram which illustrates the structure of the ion exchange resin bed in a desalting tower. It is a flow block diagram of the test apparatus used in the Example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Reactor, 2, 3 ... Turbine, 4 ... Moisture separator, 5 ... Condenser, 6 ... Condensate filtration device, 7 ... Condensate demineralizer, 8 ... Reactor purification system, 10 ... Desalination Tower, 11 ... ion exchange resin bed, 12 ... resin strainer, 13 ... recirculation pump, 14 ... mixed bed, 15a ... upper layer part, 15b ... lower layer part, 16a ... upper layer part, 16b ... lower layer part, 17a ... upper layer part, 17b: middle layer portion, 17c: lower layer portion.

Claims (14)

In a condensate demineralization method for demineralizing condensate from a nuclear power plant with an ion exchange resin,
It consists of a mixed bed in which a strongly acidic gel type cation exchange resin and a strongly basic type 1 porous anion exchange resin having a crosslinking degree in the range of 1% to 4% are uniformly mixed, and the mixed bed comprises the anion resin. The organic matter eluted from the cation exchange resin by bringing condensate into contact with an ion exchange resin bed having a mixed bed uniformly mixed so that the abundance ratio is within the design standard value ± 5% over the entire mixed bed. A condensate desalination method, wherein the desalination treatment is carried out while removing . In a condensate demineralization method for demineralizing condensate from a nuclear power plant with an ion exchange resin,
(A) a mixed bed in which a strongly acidic gel type cation exchange resin and a strongly basic type 1 porous anion exchange resin having a crosslinking degree in the range of 1% to 4% are uniformly mixed, An upper layer portion composed of a mixed bed uniformly mixed so that the abundance ratio of the anionic resin is within a design standard value ± 5% over the entire mixed bed;
(B) a condensate dewatering process wherein decondensation is performed while removing the organic substances eluted from the cation exchange resin by bringing the condensate into contact with an ion exchange resin bed having a lower layer made of an anion exchange resin. Salt method. In a condensate demineralization method for demineralizing condensate from a nuclear power plant with an ion exchange resin,
(A) an upper layer made of a cation exchange resin;
(B) a mixed bed in which a strongly acidic gel type cation exchange resin and a strongly basic type 1 porous anion exchange resin having a crosslinking degree in the range of 1% to 4% are uniformly mixed, A condensate is brought into contact with an ion exchange resin bed having a lower layer portion composed of a mixed bed uniformly mixed so that the abundance ratio of the anion resin is within a design standard value ± 5% over the entire mixed bed. A condensate desalting method comprising performing desalting while removing organic substances eluted from the cation exchange resin . In a condensate demineralization method for demineralizing condensate from a nuclear power plant with an ion exchange resin,
(A) an upper layer made of a cation exchange resin;
(B) a mixed bed in which a strongly acidic gel type cation exchange resin and a strongly basic type 1 porous anion exchange resin having a crosslinking degree in the range of 1% to 4% are uniformly mixed, A middle layer portion composed of a mixed bed uniformly mixed so that the abundance ratio of the anionic resin is within a design standard value ± 5% over the entire mixed bed;
(C) Condensate dewatering, wherein decondensation treatment is performed while removing the organic substances eluted from the cation exchange resin by bringing the condensate into contact with an ion exchange resin bed having a lower layer portion made of an anion exchange resin. Salt method. The condensate desalting method according to any one of claims 1 to 4, wherein the organic substance contains polystyrene sulfonic acid. As a cation exchange resin, condensate demineralizer method according to any one of claims 1 to 5, the degree of crosslinking is characterized by using a 12% to 16% of the strongly acidic gel-type cation exchange resin. As a cation exchange resin, condensate demineralizer method according to any one of claims 1 to 5, the degree of crosslinking is characterized by using 4-7% of the strongly acidic gel-type cation exchange resin. In a condensate demineralizer for a nuclear power plant that demineralizes condensate with an ion exchange resin,
Condensate is brought into contact with an ion exchange resin bed having a mixed bed in which a strongly acidic gel type cation exchange resin and a strongly basic type 1 porous anion exchange resin having a crosslinking degree in the range of 1% to 4% are uniformly mixed. And performing a desalting treatment while removing organic substances eluted from the cation exchange resin . In a condensate demineralizer for a nuclear power plant that demineralizes condensate with an ion exchange resin,
(A) an upper layer portion comprising a mixed bed in which a strongly acidic gel type cation exchange resin and a strongly basic type 1 porous anion exchange resin having a crosslinking degree in the range of 1% to 4% are uniformly mixed;
(B) a condensate dewatering process wherein decondensation is performed while removing the organic substances eluted from the cation exchange resin by bringing the condensate into contact with an ion exchange resin bed having a lower layer made of an anion exchange resin. Salt equipment. In a condensate demineralizer for a nuclear power plant that demineralizes condensate with an ion exchange resin,
(A) an upper layer made of a cation exchange resin;
(B) having a lower layer portion comprising a mixed bed in which a strongly acidic gel type cation exchange resin and a strongly basic type 1 porous anion exchange resin having a crosslinking degree in the range of 1% to 4% are uniformly mixed. A demineralization apparatus for demineralization, wherein a demineralization treatment is performed while contacting condensed water with an ion exchange resin bed to remove organic substances eluted from the cation exchange resin . In a condensate demineralizer for a nuclear power plant that demineralizes condensate with an ion exchange resin,
(A) an upper layer made of a cation exchange resin;
(B) a middle layer portion comprising a mixed bed in which a strongly acidic gel type cation exchange resin and a strongly basic type 1 porous anion exchange resin having a crosslinking degree in the range of 1% to 4% are uniformly mixed;
(C) Condensate dewatering, wherein decondensation treatment is performed while removing the organic substances eluted from the cation exchange resin by bringing the condensate into contact with an ion exchange resin bed having a lower layer portion made of an anion exchange resin. Salt equipment. The condensate demineralizer according to any one of claims 8 to 11, wherein the organic substance contains polystyrene sulfonic acid. As a cation exchange resin, the degree of crosslinking condensate demineralizer according to any one of claims 8 to 12 which comprises using a 12% to 16% of the strongly acidic gel-type cation exchange resin. The condensate demineralizer according to any one of claims 8 to 12 , wherein a strongly acidic gel-type cation exchange resin having a crosslinking degree in the range of 4 to 7% is used as the cation exchange resin.

Images